ProcedurProgramavimas_1.08

#include <iostream>
#include <iomanip>

using namespace std;
int main()
{
long double x1, y1, x2, y2, x3, y3, q;
cin>>x1;
cin>>y1;
cin>>x2;
cin>>y2;
cin>>x3;
cin>>y3;

q=(((x1-x3)*(y2-y3))-((x2-x3)*(y1-y3)))/2;
if (q<0) {q=-q;
    }

cout<<fixed<<setprecision(1)<<q<<endl;
    return 0;
}